Magnetic recording disk drive with shingled writing and wide-area thermal assistance

Abstract

A thermally-assisted recording (TAR) disk drive uses a “wide-area” heater with “shingled” recording. In shingled recording, the write head pole tip is wider than the read head in the cross-track direction and writes magnetic transitions by making a plurality of consecutive circular paths that partially overlap. The non-overlapped portions of adjacent paths form the data tracks, which are thus narrower than the width of the write pole tip. The data tracks are grouped into annular bands and when data is to be rewritten, all of the data tracks in an annular band are also rewritten. The wide-area heater may be a waveguide with an output end that generates a heated area on the disk recording layer which is wider than the cross-track width of the write pole tip. It has been determined that the use of a wide-area heater with shingled recording does not result in any significant adjacent track erasure (ATE).

Description

TECHNICAL FIELD[0001]This invention relates generally to a thermally-assisted recording (TAR) system, in which data are written while the magnetic recording layer is at an elevated temperature, and more specifically to a TAR disk drive with a “wide-area” heater that heats an area of the disk wider than the data track to be recorded.BACKGROUND OF THE INVENTION[0002]In magnetic recording disk drives the magnetic material (or media) for the recording layer on the disk is chosen to have sufficient coercivity such that the magnetized data regions that define the data “bits” are written precisely and retain their magnetization state until written over by new data bits. As the areal data density (the number of bits that can be recorded on a unit surface area of the disk) increases, the magnetic grains that make up the data bits can be so small that they can be demagnetized simply from thermal instability or agitation within the magnetized bit (the so-called “superparamagnetic” effect). To ...

AI Technical Summary

Benefits of technology

The invention is about a new type of disk drive that uses a wide-area heater to help with writing data on the disk. The heater heats up a wider area than the actual writing area, which helps to reduce errors in the data. The data is written by making multiple circular paths that partially overlap, and the data tracks are organized into annular bands. When data needs to be rewritten, all the data tracks in an annular band are rewritten. The use of the wide-area heater has been found to not cause any significant errors in the data, and the heated area is much larger than the actual writing area. Overall, this new technology helps to improve the accuracy and reliability of writing data on disks.

Problems solved by technology

Obviously, the switching field cannot exceed the write field capability of the recording head, which currently is limited to about 12 kOe for perpendicular recording.

Also, even in the absence of a magnetic field, the heating of adjacent data tracks will accelerate the thermal decay rate over that at ambient temperature and thus data loss may occur.

While providing the advantage of less ATE, small-area heaters are difficult to fabricate.

Also, because of the relatively inefficient heat transfer the heater temperatures required to reach a desired media temperature are very high.

However, wide-area heaters have been shown to result in substantial ATE because the adjacent tracks are repeatedly exposed to a combination of both the fringe fields from the write head and the heat from the wide-area heater.

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